- 期刊
A Computed Tomographic Study of the Bonwill Triangle for the Taiwanese Population
摘要
Purpose: The distances between the mandibular incisors and condyle or the distance between the right and left condyles are among the factors that affect the correct positioning of casts. Most dentists use the average value of the Bonwill triangle to position casts in an articulator if a face-bow is not used. However, there is some controversy as to whether the distance, as described by Bonwill, is consistent. The aim of this study, therefore, was to provide dentists with a reference value for the Bonwill triangle of the Taiwanese population for use in mounting casts in an articulator. Material and methods: Ninety-nine computerized tomographic (CT) images of the heads of patients treated at China Medical University Hospital (48 females and 51 males; mean age: 40 years) were selected. The distance between the contact points of the mandibular central incisors' incisal edges and the central point of each condyle and the distance between the central points of both condyles were calculated using Mimics 10.01 software. Results: The results showed that the distances between the mandibular incisors and the centers of the left and right condyles were 104 mm and 103 mm, respectively, while the distance between both condyles was 106 mm. Together, these distances approximately formed an equilateral triangle, as proposed by Bonwill, although the resulting triangle was slightly larger than that suggested by Bonwill. Also, while the length of the left side was slightly longer than that of the right side, the distance of both sides decreased with age above 30 years old, whereas the distance between the centers of the condyles increased with age until the age of 50 and then decreased. Conclusion: This study showed that, among Taiwanese, the size of the Bonwill Triangle is larger for males and changes with age. The study also confirmed that the Bonwill triangle provides a feasible means of mounting casts in an articulator if a face-bow transfer cannot be employed.